Convert XML to JSON in PHP
http://www-128.ibm.com/developerworks/views/web/libraryview.jsp?type_by=Articles

Nathan, Senthil, Edward J Pring and John Morar
IBM
2007

Abstract:

With the growing popularity of Web 2.0, a new data interchange format called JavaScript Object Notation (JSON) is emerging as a useful way to represent data in the business logic running on browsers. Learn how PHP-based server programs can convert XML-formatted enterprise application data into JSON format before sending it to browser applications.